1. Field of the Invention
The present invention relates generally to coupling devices, and more particularly to a coupling which is particularly adapted for use in turbogenerators.
2. Description of the Prior Art
Couplings for connecting together the ends of two shafts, having coupling flanges fixedly secured thereto, for transmitting large torques therebetween by means of friction generated between the faces of the two coupling flanges produced by axial thrust forces, have long been known. The exterior diameters of the two coupling flanges are generally equal and the axial thrust forces are usually impressed upon the coupling flanges by means of axial screw bolts (see CH-PS 335 573) or shrunk-on sleeve devices (see CH-PS 457 053). These known configurations can thus be used to advantage when the exterior diameters of the coupling flanges are the same and there are no other special limitations imposed upon the system.
In turbogenerator construction, however, there is needed a rigid friction-clutch coupling of the type discussed for transmitting large torques from the turbine shaft to the generator shaft, the coupling flange secured to the turbine shaft being as large as desired, however the flange secured upon the generator shaft has the limitation that its exterior diameter must be smaller than the inside diameter of the turbine end closure, which during assembly must be housed over the generator coupling flange and the coil end thereof. After installation of the end closure, the exterior diameter can then, if deemed expedient, be increased, since the end closure is only rarely disassembled.
The modern development in turbogenerator construction has been in the direction of smaller generator shafts, made possible by improved cooling of rotor windings and the use of high-grade materials, and such shafts must now accommodate even greater torques. As a result, a correspondingly smaller coupling is called for to transmit the torque from the turbine shaft to the generator shaft. The friction which can be developed between the now significantly smaller coupling flanges no longer suffices for transmission of the torques, so that additional means for this purpose are necessary.